Facebook isn't innocuous and has a high negative load and reputation. Tack the word "secret" in front of some internal research they did and it puts a darker shade on something every company does (internal research).
Something like ‘Secret Facebook network architecture’ is rather neutral.
“Tesla’s secret battery program”
Neither has negative connotation to me.
Like you said, I think it’s because Facebook regularly acts unethically in public view. Anything they do in secret or private will be viewed with even more suspicion.
> Kellogg’s secret research to make cereal taste better
to me, this sounds negative
> Tesla’s secret battery program
to me this does not sound negative.
This is 100% your opinion.